A group of people tried joining a gym to see if it would help them to lose weight. This table shows the relationship between the number of weeks since each person joined the gym and the number of pounds they have lost. Which function best models the data?

y=−0.43x+2.5

y=−1.5x+5.5

y = 0.31x + 0.12

y=0.75x−3.5